1. Field of the Invention
The invention relates to a sensor device for detecting moisture on a windscreen comprising a transmitter and a receiver and optics arranged between the transmitter and the receiver, wherein the optics comprises an upper plane for connection to a windscreen, and wherein the optics comprises a decoupling region serving to decouple the electromagnetic rays from the optics into the windscreen, and a coupling region serving to couple the electromagnetic radiation from the windscreen into the optics. Furthermore the invention relates to optics for a sensor device of this kind and a motor vehicle with a windscreen and a sensor device arranged thereon.
2. Brief Discussion of the Related Art
The DE 40 06 174 C1 has disclosed a sensor device of the kind mentioned in the beginning. The windscreen has an optics arranged on it, which at one end has radiation introduced into it from a radiation transmitter. The radiation is reflected multiple times in the optics and in the plane supported against the topside of the optics. Decoupling of the rays from the windscreen depends upon the degree of wetting of the windscreen. The other end of the optics has a receiver arranged on it, which supplies a signal inversely proportional to the amount of precipitation. The sensor device operates according to the optical principle of total reflection.
The basic problem consists in that the space available for the sensor device is becoming increasing smaller. This means that the surface of the optics forming the sensing region, is also reduced in size. As a result a signal of diminished accuracy is obtained.